of canton



Patented Sept. 13, 1932 UNITED STA-TES.

TRACY v. BUCKWALTER, or CANTON, onromssmNoa To THE'TIMKEN :ROLLER BEAR- ING CCMrANY, oF CANToN,on1 o, A CORPORATION Cromo SEPABABLE DBILL BIT Application and october 2, 1930.A seriaiNo. 485,851. i

My invention relates to detachable bit con structions Jfor rock and other drills. It has for its principal object a construction that is very strong so as to withstand the heavy 5 shocks to which such devices are subjected and and in which the threads lof the various parts are so constructed that they will not bind.

Rotary drills, such as rock drills, are subpect to heavy thrust and to strains tending to snap the parts; so that it is necessary to have a very rugged construction. The bits of such drills, particularly rock drills,l wear quite rapidly; and it is a greatadvantage to have the bit detachable from the drill rod so that it may be removed to be sharpened or replaced by a new bit, and in such detachable constructions it is necessary that the parts be made'so that they will not seize or bind during the drilling operation. Previous detachable bit constructions have been too weak or too com'- plicated and expensive or the parts yhave become so tightly secured together during the drilling operation that removal of the bit is quite difficult or impossible. The present invention provides a detachable bit construction in which the parts are greatly strengthened, in which the threads of the several parts are so constructed that they do not bind in use and which is simple in construction. The invention consists principally in the detachable bit and in the parts and combinations and arrangements of parts hereinafter described and claimed.

In the accompanying drawing,

Fig. 1 is an elevation of a detachable bit construction embodying my invention,

Fig. 2 is a-view similar to Fig. 1, showing in longitudinal section the coupling member that secures the bit and drill rod together,

Fig 3 is a view similar to Fig. 2, showing the several part-s separated fromv each other,

Fig. 4 is an end'view of the bit; and

Fig. 5 is an enlarged view of the inter-engaging threads of the drill rod and coupling 45 member. l

The drawing illustrates a detachable bit construction including a drill rod 1, a detachable bit 2 and a coupling member 3 securingA the bit to the drill rod. The end 4 of the drill rod 1 is tapered and threaded and the shank portion 5 of the bit 2 is likewise tapered and threaded.` Thecoupling 3 is interiorly threaded to receive the threaded portions of the drill rod 1 and of the bit 2. As said threaded portions are tapered,v the coupling increases in thickness toward its middle 6, so that its strength is greatest at the middle, which is the joint or gap between the drill rod and the bit.

In order to prevent binding of the threads, the face or thrust side 7 of each thread is as nearly as possible perpendicular of the axis of the drill rod and bit. The top or crest 8 of each tooth is flattened, or curved on a relatively long radius, so that there is a space 9 between the crest of each tooth and the bot-a tom of the groove in which it lits.

The thread construction results in the thrust being taken up by a surface that is almost perpendicular to the direction of the thrust, so that the thrust does not cause the threads to bind. The provision of the space at the crest of each tooth likewise minimizes the likelihood of the teeth binding. The tapered construction ofthe threaded portions provides the coupling member with its greatest strength at its middle, so that the likelihood of the coupling breaking is greatly diminished.

What I claim is:

1. A detachable bit construction comprising a drill rod having a tapering threaded end portion, a bit having a tapering threaded shank portion and an interiorly threaded coupling member receiving said drill rod and said bit shank, the crest of each thread being shaped to leave a space between it and the bottom of the groove in which it fits, both faces of each thread engaging adjacent threads.

faces of said threaded portions making almost a right angle with the axis of said drill rod. v 3. A. detachable bit-construction comprising a. drill rod haviiigataperilg threaded end portion2 a bit havin a-ltapering threaded shank portlou and anfinteriorly 'threaded-y coupling member receiving said drill rod and said bitshank, both facesno'f each thread con-jf tact throughout with `the faces of adjacent l0 threads of the cooperating member, exceptv that the crest of each thread is runded od on a large radius, thereby leaving a space between said crest and the base portions ofad jacent teeth. f w Signed at Canton, Ohio, this 23d day of] Sept.,193o.

TRACY-V. B UCIGVALER; n 

